Securize the creation of the VLC instance

CHANGELOG.md

@@ -31,6 +31,10 @@
 
 ## Unreleased
 
+### Added
+
+- When using VLC, the player will properly crash if unexpected instance parameters are given.
+
 ### Changed
 
 - The discovery of instrumental file or track is now delegated to the feeder, which means that this data is given by the server. There are no re-discovering processes, but some checks are performed (whether the instrumental file exists, and if the instrumental track exists).

src/dakara_player/media_player/vlc.py

@@ -123,8 +123,10 @@ def init_player(self, config, tempdir):
         )
 
         # VLC objects
-        self.instance = vlc.Instance(config_vlc.get("instance_parameters") or [])
-        self.player = self.instance.media_player_new()
+        self.instance = get_instance(config_vlc.get("instance_parameters"))
+
+        player = self.instance.media_player_new()
+        self.player = player
         self.event_manager = self.player.event_manager()
 
         # vlc callbacks
@@ -786,6 +788,38 @@ def get_metadata(media):
     raise ValueError("This media has no set metadata")
 
 
+def get_instance(instance_parameters=None):
+    """Get a VLC instance with parameters.
+
+    Args:
+        instance_parameters (list of str): List of parameters. Must be in the
+            form "--option=value".
+
+    Returns:
+        vlc.Instance: New instance.
+
+    Raises:
+        UnavailableInstanceError: If an instance cannot be obtained without
+            parameters.
+        UnexpectedInstanceParameterError: If unexpected parameters are
+            passed.
+    """
+    # if no parameters are passed, the instance should never be None
+    if not instance_parameters:
+        instance = vlc.Instance()
+        if instance is None:
+            raise UnavailableInstanceError("Unable to get a VLC instance")
+
+        return instance
+
+    # if parameters are passed, an unexpected parameter makes the instance None
+    instance = vlc.Instance(instance_parameters)
+    if instance is None:
+        raise UnexpectedInstanceParameterError("Unexpected VLC instance parameter")
+
+    return instance
+
+
 class Media:
     """Media object."""
 
@@ -804,3 +838,11 @@ def __init__(self, *args, track_id_audio=None, **kwargs):
 
 class VlcTooOldError(DakaraError):
     """Error raised if VLC is too old."""
+
+
+class UnexpectedInstanceParameterError(DakaraError):
+    """Error raised when passing incorrect parameters to  the VLC instance."""
+
+
+class UnavailableInstanceError(DakaraError):
+    """Error raised when a VLC instance cannot be obtained."""

tests/integration/test_media_player_vlc.py

@@ -16,7 +16,10 @@
 from func_timeout import func_set_timeout
 
 from dakara_player.media_player.base import IDLE_BG_NAME, TRANSITION_BG_NAME
-from dakara_player.media_player.vlc import METADATA_KEYS_COUNT, MediaPlayerVlc
+from dakara_player.media_player.vlc import (
+    METADATA_KEYS_COUNT,
+    MediaPlayerVlc,
+)
 from dakara_player.mrl import mrl_to_path
 from tests.integration.base import TestCasePollerKara
 

tests/unit/test_media_player_vlc.py

@@ -24,7 +24,10 @@
 )
 from dakara_player.media_player.vlc import (
     MediaPlayerVlc,
+    UnavailableInstanceError,
+    UnexpectedInstanceParameterError,
     VlcTooOldError,
+    get_instance,
     get_metadata,
     set_metadata,
 )
@@ -1422,3 +1425,29 @@ def test_not_in_list_default_return(self, mocked_is_playing_this):
 
         with self.get_instance() as (player, _, _):
             self.assertEqual(function_decorated(player), 42)
+
+
+@patch("dakara_player.media_player.vlc.vlc", autospec=True)
+class GetInstanceTestCase(TestCase):
+
+    def test_parameters_unexpected(self, mocked_vlc):
+        """Test to pass unexpected parameters."""
+        mocked_vlc.Instance.return_value = None
+        with self.assertRaises(UnexpectedInstanceParameterError):
+            get_instance(["parameter"])
+
+    def test_parameters(self, mocked_vlc):
+        """Test to pass parameters."""
+        self.assertIs(mocked_vlc.Instance.return_value, get_instance(["parameter"]))
+        mocked_vlc.Instance.assert_called_with(["parameter"])
+
+    def test_no_parameters_unavailable(self, mocked_vlc):
+        """Test unavailable instance."""
+        mocked_vlc.Instance.return_value = None
+        with self.assertRaises(UnavailableInstanceError):
+            get_instance()
+
+    def test_no_parameters(self, mocked_vlc):
+        """Test instance."""
+        self.assertIs(mocked_vlc.Instance.return_value, get_instance())
+        mocked_vlc.Instance.assert_called_with()